Asphalt Calculator
About Asphalt Calculation
The asphalt calculator estimates the pavement volume, asphalt mix consumption per 1 m2, and the material quantity in tonnes, including an allowance for losses. The calculation is based on the area, compacted layer thickness, and density of the selected mix.
It is suitable for preliminary estimates of asphalt quantities for paths, parking areas, driveways, and other paved surfaces.
Guidelines and recommendations
Calculating the paved area
Area is determined by the shape of the site. For a rectangle, length is multiplied by width. For a circular area, the circle area formula is used. If the area is already known, it is used directly in subsequent calculations.
Rectangle area = length × width
Circle area = π × diameter2 / 4
All site dimensions are expressed in metres and the area in m2. The calculation assumes that the entire specified area is paved evenly.
Layer thickness and asphalt volume
Layer thickness refers to the asphalt mix after compaction. This is the thickness used to calculate the finished pavement volume. No additional compaction factor is applied because the mix density also refers to its compacted state.
Pavement volume is calculated by multiplying the area by the layer thickness. Since thickness is entered in centimetres, it is divided by 100 to convert it to metres.
Volume (m3) = area (m2) × thickness (cm) / 100
For example, an area of 50 m2 with a thickness of 5 cm produces a finished pavement volume of 2.5 m3. The calculation assumes a uniform layer thickness and does not account for local variations in the base surface.
Asphalt mix density
Density determines the mass of one cubic metre of compacted asphalt. It depends on the mix composition, aggregate properties, and air void content. The following approximate values are used for preliminary estimates:
- Asphalt concrete (AC) - 2400 kg/m3.
- Stone mastic asphalt (SMA) - 2350 kg/m3.
- Porous asphalt (PA) - 2100 kg/m3.
These are calculation assumptions, not mandatory standard density values. For a more accurate mass estimate, use the actual density specified by the supplier for the particular mix.
Asphalt consumption per 1 m²
Consumption per unit area indicates how many kilograms of mix are needed for one square metre of pavement at the chosen thickness. It is calculated by multiplying density by layer thickness converted into metres.
Consumption (kg/m2) = density (kg/m3) × thickness (cm) / 100
At a density of 2400 kg/m3, consumption is 72 kg/m2 for a 3 cm layer, 120 kg/m2 for 5 cm, and 192 kg/m2 for 8 cm. These figures exclude the allowance for losses.
Allowance for losses and quantity to order
Allowance for losses increases the calculated quantity of mix by a specified percentage. It covers possible losses during transport, unloading, spreading, and levelling. The default allowance is 5%, and it can be adjusted.
Volume including allowance = pavement volume × (1 + allowance (%) / 100)
Quantity to order is calculated by multiplying the volume including the allowance by the mix density. The result is converted from kilograms to tonnes.
Mass (t) = volume including allowance (m3) × density (kg/m3) / 1000
For example, with a pavement volume of 2.5 m3, a density of 2400 kg/m3, and a 5% allowance, the volume including the allowance is 2.625 m3, and the quantity to order is 6.3 t. The allowance increases the ordered amount, not the thickness of the finished pavement.
Calculation precision
Calculation precision depends mainly on the accuracy of the layer thickness and mix density. Area is displayed to 0.01 m2, volume to 0.001 m3, mass to 0.001 t, and consumption to 0.01 kg/m2. Rounding applies only to displayed results and does not reduce precision in intermediate calculations.
European standards
European standards in the EN 13108 series, Bituminous mixtures - Material specifications, apply to asphalt mixes. The main documents for the mix types covered here are:
- EN 13108-1 - Asphalt concrete.
- EN 13108-5 - Stone mastic asphalt.
- EN 13108-7 - Porous asphalt.
- EN 12697-6 - Bituminous mixtures. Test methods. Determination of bulk density of compacted specimens.
These standards set requirements for the respective mix types and provide methods for measuring their properties. The specified pavement thickness, mix composition, and required density characteristics are selected according to the pavement's intended use, service conditions, and project requirements.
FAQs
How many tonnes of asphalt are needed for 100 m²?
For a pavement thickness of 5 cm and a density of 2400 kg/m3, 12 t of asphalt mix are required without an allowance. With a 5% allowance, the quantity to order is 12.6 t. Different thickness or density values change the required amount proportionally.
Why does the same area require different amounts of asphalt?
Asphalt mass depends not only on the paved area but also on layer thickness and mix density. For example, increasing thickness from 4 to 6 cm increases the required mass by 50% when the area stays the same. Differences in density also affect the final tonnage.
What asphalt thickness is commonly used?
A top layer of around 3-4 cm is often used for pedestrian paths, while around 4-6 cm is common for areas and driveways used by passenger cars. Heavier loads may require thicker pavements or multilayer structures. The actual thickness depends on the intended use, mix properties, and base construction.
How accurately can asphalt mass be calculated?
With known site dimensions, layer thickness, and actual mix density, the calculation provides a reasonably accurate estimate of the theoretical material requirement. The main deviations come from uneven layer thickness, the condition of the base, and actual losses. An additional allowance is therefore commonly included when ordering asphalt.
How much extra asphalt should be allowed for losses?
An allowance of around 5-10% is often used for preliminary estimates. A more complex site shape, numerous edges, or manual spreading may call for a larger allowance. The percentage should reflect expected laying losses rather than compensate for an incorrectly chosen layer thickness.